Question: A $16\dfrac12$ kilometer stretch of road needs repairs. Workers can repair $2\dfrac14$ kilometer of road per week. How many weeks will it take to repair this stretch of road?
Solution: We can think about this problem like this: ${\text{number of weeks}} = \dfrac{C{\text{total length of road}}}{{\text{length repaired each week}}}$ ${\text{?}} = C{16\dfrac12} \div {2\dfrac{1}{4}}$ $\begin{aligned} C{16\dfrac12}&=C{\dfrac{33}{2}} \\\\ {2\dfrac{1}{4}}&={\dfrac{9}{4}} \\\\ {\text{?}} &=C{\dfrac{33}{2}} \div {\dfrac{9}{4}} \end{aligned}$ $\begin{aligned} C{\dfrac{33}{2}} \div {\dfrac{9}{4}}&=C{\dfrac{33}{2}}\times\dfrac{4}{9} \\\\ &=\dfrac{33\times4}{2\times9} \\\\ &=\dfrac{132}{18} \\\\ &=\dfrac{22}{3} \end{aligned}$ It will take $\dfrac{22}{3}$ weeks to repair this stretch of road.